首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   607415篇
  免费   4542篇
  国内免费   1397篇
化学   290471篇
晶体学   9116篇
力学   33366篇
综合类   16篇
数学   85896篇
物理学   194489篇
  2021年   5607篇
  2020年   5950篇
  2019年   6946篇
  2018年   9856篇
  2017年   10109篇
  2016年   13430篇
  2015年   7147篇
  2014年   12584篇
  2013年   26901篇
  2012年   21152篇
  2011年   25121篇
  2010年   19497篇
  2009年   19842篇
  2008年   23417篇
  2007年   23126篇
  2006年   21162篇
  2005年   18471篇
  2004年   17491篇
  2003年   15814篇
  2002年   15978篇
  2001年   17678篇
  2000年   13463篇
  1999年   10420篇
  1998年   9103篇
  1997年   8765篇
  1996年   8139篇
  1995年   7233篇
  1994年   7184篇
  1993年   7062篇
  1992年   7429篇
  1991年   8005篇
  1990年   7705篇
  1989年   7642篇
  1988年   7184篇
  1987年   7381篇
  1986年   6952篇
  1985年   8571篇
  1984年   8812篇
  1983年   7415篇
  1982年   7633篇
  1981年   7213篇
  1980年   6893篇
  1979年   7619篇
  1978年   7749篇
  1977年   7909篇
  1976年   8009篇
  1975年   7463篇
  1974年   7304篇
  1973年   7546篇
  1972年   5860篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

The problem of the minimax testing of the Poisson process intensity \({\mathbf{s}}\) is considered. For a given intensity \({\mathbf{p}}\) and a set \(\mathcal{Q}\), the minimax testing of the simple hypothesis \(H_{0}: {\mathbf{s}} = {\mathbf{p}}\) against the composite alternative \(H_{1}: {\mathbf{s}} = {\mathbf{q}},\,{\mathbf{q}} \in \mathcal{Q}\) is investigated. The case, when the 1-st kind error probability \(\alpha \) is fixed and we are interested in the minimal possible 2-nd kind error probability \(\beta ({\mathbf{p}},\mathcal{Q})\), is considered. What is the maximal set \(\mathcal{Q}\), which can be replaced by an intensity \({\mathbf{q}} \in \mathcal{Q}\) without any loss of testing performance? In the asymptotic case (\(T\rightarrow \infty \)) that maximal set \(\mathcal{Q}\) is described.

  相似文献   
2.
3.
4.
5.
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius r=50 nm and different distance d between the disks centers (from d=12 nm to d=2R=100 nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices.  相似文献   
6.
7.
8.
9.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films were investigated using a number of techniques. A high saturation magnetic induction up to B s = 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed, which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of the composition. The text was submitted by the authors in English.  相似文献   
10.
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号